Two types of engine output drive arrangements are possible--viz.: engines providing right-hand rotation to the output shaft and engines providing left-hand rotation to the output shaft. The right-hand engine is more prevalent. However, many of the angle drive, or V-drive, arrangements in the United States of America are left-hand drive systems such as those built by the Allison Division of General Motors corporation. These drive systems are found mostly in buses with diesel engines. V-drives are, however, becoming more popular in Europe, and the European market prefers right-hand drive engines and fight-hand transmissions such as the ZF-Ecomat or those built by Voith.
Currently available transmissions must provide a plurality of forward drive ratios and one or more reverse ratios to take full advantage of the engine speed range. The majority of such transmissions are adapted for left-hand drive engines, and as such, are not readily usable with right-hand drive engines without some means, such as a gearing assembly, to effect rotational direction reversing. Some right-hand drive transmissions have been thus modified to provide left-hand output from right-hand engines. However, these transmissions have traditionally had the V-drive gearing at the transmission output and the drive reversing gears are added between the transmission output and the V-drive gearing input. While these systems are satisfactory, they do require high torque capacity gears in the rotational reversing portion of the drive train in order to permit the transfer of the transmission output torque to the vehicle drive mechanism. Also, these systems require at least three gear meshes to accomplish rotational direction reversal.
The V-drive arrangements are generally employed with an engine that is oriented transversely of the vehicle. The input portion--i.e.: torque converter and the drive ratio gearing--of a right-hand transmission is located on the engine centerline. So disposed, the transverse dimension of the vehicle required to accommodate a right-hand drive arrangement is greater than that required by a left-hand drive arrangement. Even the added gear meshes at the transmission output increase the dimensional requirement.